Reliability processing methods and systems in the networking of metro ethernet network providing multi-service

ABSTRACT

A reliability processing method in networking of Metro Ethernet Network providing multi-service includes: establishing a Virtual Router Redundancy Protocol (VRRP) group with at least two service control gateways, establishing network connections between an access device (UPE) and the service control gateways in the Virtual Router Redundancy Protocol group by a Virtual Private LAN Service (VPLS); performing Layer 2 service and Layer 3 service processing, after active and standby service control gateways in the Virtual Router Redundancy Protocol group are determined according to a processing result of a Virtual Router Redundancy Protocol message. Therefore, the reliability of the Layer 2 and Layer 3 services of the MAN may be sufficiently guaranteed, and the overhead of the system may be reduced significantly.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/536,030, filed on Aug. 5, 2009, which is a continuation ofInternational Application No. PCT/CN2007/002813, filed on Sep. 25, 2007.The International Application claims priority to Chinese PatentApplication No. 200710000420.X, filed on Feb. 5, 2007. Theafore-mentioned patent applications are hereby incorporated by referencein their entireties.

FIELD OF THE INVENTION

The present invention relates to the reliability processing techniquefor Metropolitan (Metro) Ethernet data, and more particularly, to thereliability processing methods and systems in the networking of MetroEthernet Network providing multi-service.

BACKGROUND

The Ethernet technique originates from the Local Area Network (LAN).Moreover, the Ethernet is a standard technique with goodinteroperability, support from wide software and hardware, and low cost.Meanwhile, it is a media-independent bearer technique which mayinterface with different transmission medium such as the twisted pairs,cable and various optical fibers, thereby avoiding the cost of rewiring.Therefore, the Ethernet networking technique is being significantlydeveloped, and is becoming the bearer network for the Metro Area Network(MAN).

However, for the operable telecom-level Metro Ethernet, there are manyproblems to be solved regarding the architecture, network management,protection technique, Quality of Service (QoS) technique, as well as theservice provision. With respect to the service protection, the Ethernetis originally designed for the internal applications for LAN users,without guarantee from a security mechanism. After it is extended to thetelecom-level Metro Ethernet, a more reliable security mechanism isrequired in order to provide the reliability guarantees for the telecomservices within the MAN. The Ethernet may be applied in the Metrotelecom network environment as a telecom-level multi-service platformonly if the major problem above is solved properly.

The conventional techniques involved in the present invention arebriefly illustrated below.

1. Multi-Protocol Label Switching (MPLS) Technique

The MPLS belongs to the network architecture of the 3^(rd) generation,and is a high-speed IP backbone switching standard of the new generationproposed by the Internet Engineering Task Force (IETF). The MPLS is aswitching technique with the Layer 3 route incorporating the Layer 2attributes, and introduces a label-based mechanism, in which the routingand data forwarding are separated and the path by which a packet passesthrough the network is specified by the label.

2. Virtual Private LAN Service (VPLS) Technique

The VPLS is a service providing a similar LAN on the MPLS network. TheVPLS enables users at dispersed geographical locations to access thenetwork simultaneously and access each other, as if these locations areconnected to the LAN directly. The VPLS enables the users to extendtheir LANs to the MAN, even to the Wide Area Network (WAN).

3. Virtual Router Redundancy Protocol (VRRP) Technique

Generally, all the hosts in an internal network are configured with thesame default route, pointing to the export gateway, thereby implementingthe communications between the hosts and the external networks. If theexport gateway is in fault, the communications between the hosts and theexternal networks will be interrupted. It is a common method toconfigure multiple export gateways in order to improve the systemreliability. However, the routing among the multiple export gatewaysbecomes a problem to be solved. The VRRP is a fault-tolerant protocol,in which the implementation of the physical devices and logical devicesis separated and the default gateway of the terminal IP device isredundancy backed up, so that a standby router will take over theforwarding work upon one router is out of work, thereby providingtransparent switching to the user, and solving the problem noted aboveproperly.

In the conventional art, the services deployed on the Metro Area Networkgenerally include many types of services, such as the Internet service,Virtual Private Network (VPN) service, Broadcast TV (BTV) service, andVideo on demand/Voice over IP (VOD/VOIP) service. In the practicalnetworking, the network architecture includes a backbone layer, and aconvergence & access layer. Service Routers (SRs) are deployed at thenetwork edge of the backbone layer and the convergence & access layer toimplement the functions, such as the MAN service control, user control,and security control. Generally, in order to ensure the reliability ofthe network, the network service routers are disposed in anactive-standby manner, so that the standby device starts to operate uponthe active device is in fault, thereby ensuring that the network servicewill not be interrupted.

For the Layer 3 network services, such as the VOD, VOIP, and Layer 3VPN, the VRRP protocol may be configured between the active and standbyservice routers, so that the related services may be switched to thestandby service router when the network is in fault or the activeservice router is in fault. However, the VRRP is a Layer 3 networkprotocol not applicable for Layer 2 services, such as the internet (PPPaccess) service, and Layer 2 VPN service. Thus, when the network is infault or the active service router is in fault, there is no highlyeffective protection method to switch the Layer 2 services for users tothe standby service router quickly. In the conventional technique, theLayer 2 service switches to the path of the standby router with aSpanning Tree Protocol (STP) algorithm. However, the STP algorithm has arelatively long convergence time, which may not satisfy the requirementof rapid switching of network services. Accordingly, a disadvantage ofthe conventional technique is the lack of an effective, rapid andreliable redundancy standby mechanism for Layers 2 and Layer 3 services.

SUMMARY

Reliability processing methods and systems in networking of a MetroEthernet Network providing multi-service are provided in variousembodiments of the present invention, to solve the problem ofreliability protection technique in the conventional art for uniformlyswitching of the various services deployed in the Metro Ethernet Networkwhen the Metro Ethernet Network is in fault.

A reliability processing method in networking of a Metro EthernetNetwork providing multi-service is provided according to an embodimentof the present invention.

The method includes: establishing a Virtual Router Redundancy Protocol(VRRP) group with at least two service control gateways (servicerouters), and establishing network connections between an access device(UPE) and the service control gateways in the VRRP group by a VirtualPrivate LAN Service (VPLS); and establishing Layer 2 service and Layer 3service connections between an active service control gateway and theaccess device after active and standby service control gateway in theVRRP group are determined according to a processing result of a VRRPmessage, and performing Layer 2 service and Layer 3 service processing.

A reliability processing system in networking of a Metro EthernetNetwork providing multi-service is also provided according to anembodiment of the present invention.

The system includes: an access device (UPE) and at least two servicecontrol gateways, and further includes a service switching module.

The at least two service control gateways form a Virtual RouterRedundancy Protocol (VRRP) group, and the access device establishesnetwork connections with the service control gateways in the VRRP groupby a Virtual Private LAN Service (VPLS), respectively.

The service switching module is configured to establish Layer 2 serviceand Layer 3 service connections between an active service controlgateway and the access device after active and standby service controlgateways in the VRRP group are determined according to a processingresult of a VRRP message, and perform Layer 2 service and Layer 3service processing.

The beneficial effect of the embodiments of the present invention isthat when the Metro Ethernet Network is in fault, the various servicesdeployed in the Metro Ethernet Network may be switched uniformly, so asto provide protection for the reliability of the multi serviceconnections.

BRIEF DESCRIPTION OF THE DRAWING(S)

FIG. 1 is a schematic diagram of an application environment for areliability processing method in the Metro Area Network (MAN) providingmulti-service, according to an embodiment;

FIG. 2 is a schematic flowchart of implementing a reliability processingmethod in the MAN providing multi-service, according to an embodiment;and

FIG. 3 is a schematic block diagram of a reliability processing systemin the MAN providing multi-service, according to an embodiment.

DETAILED DESCRIPTION

The embodiments of the present invention are illustrated in conjunctionwith the drawings below.

In the Virtual Router Redundancy Protocol (VRRP), there are two groupsof important concepts: VRRP router and virtual router, as well as activerouter and standby router. The VRRP router refers to the router runningthe VRRP and is a physical entity; and the virtual router is a logicalconcept created by the VRRP protocol. A group of VRRP routers co-operateto constitute a virtual router. The virtual router appears to theexternal as a logical router with a unique fixed Internet Protocol (IP)address and Media Access Control (MAC) address. The routers within thesame VRRP group have two exclusive roles: active router and standbyrouter. There has and only has one active router and may have one ormore standby routers in one VRRP group. The VRRP protocol uses aselection policy to select one from the router group as the active,which is responsible for the Address Resolution Protocol (ARP) responseand forwarding the IP data packets. The other routers in the group arestandby routers in a standby status. When the active router is in faultfor some reason, a standby router may be upgraded to an active routerafter a delay of several seconds. The switching is transparent to theend users since it is very rapid and does not change the IP address andthe MAC address.

In an embodiment of the present invention, the Virtual Private LANService (VPLS) is deployed at the Convergence & Access Layer of theMetro Area Network (MAN). Multiple VPLS data links are establishedbetween a service control gateway, for example, service router (SR) andan access device, for example, User facing Provider Edge Router (UPE),for different services, where all the data links are managed uniformlyat the SR. Also, a VRRP management group is configured for each UPE atthe SR. The VRRP protocol is running between the VRRP management groupsof the active and standby SRs. The SRs set the related data links asactive or standby according to a VRRP state. An active data link maysend and receive data normally, while a standby data link sends andreceives no service data except the VRRP messages. If the network or theactive SR is in fault, a standby SR is changed to an active device bythe rapid detection mechanism of the VRRP, and the related data linksare changed to an active state, so that the data services may beswitched to the standby SR quickly. With the Bidirectional ForwardingDetection, for example, BFD for VRRP, service protection switching onthe order of milliseconds may be achieved.

With the same principle, the VPLS may be deployed at the Convergence &Access Layer of the MAN, and multiple VPLS data links are establishedbetween a service router and the UPE for different services. Also, aVRRP management group is configured for each UPE at the SR, while theVRRP management group may utilize the Layer 3 service interface. TheVRRP protocol runs between the VRRP management groups of the two SRs.The UPE manages all the service data links uniformly, and directs allthe egress interfaces for the Layer 2 and Layer 3 service data to theservice data links connected to the active SR after receiving agratuitous ARP messages issued from the active SR. If the network or theactive SR is in fault, a standby SR is changed to an active device bythe rapid detection mechanism of the VRRP, for sending a control messageto the UPE. After receiving the message, the UPE modifies the directionsof all the egress interfaces for the Layer 2 and Layer 3 service data,so that the data services may be switched to the standby service routerquickly. With the BFD for VRRP, service protection switching on theorder of milliseconds may be achieved.

In other words, the services between the service router and the UPE aretransmitted via the VPLS data links. Connectivity detection is performedbetween the active and standby service routers, and the data links areset to an active or standby state according to the detection state. Astandby data link sends and receives no data. The correct forwarding ofall the Layer 2 and Layer 3 data and the protection switching in networkfault are guaranteed by identifying the active or standby state of thedata links. Or, the UPE may direct all the egress interfaces for theLayer 2 and Layer 3 service data to the service data links connected tothe active service router after receiving a control message issued fromthe active service router, so as to achieve the correct forwarding ofthe Layer 2 and Layer 3 data as well as the protection switching innetwork fault.

FIG. 1 is a schematic diagram of an application environment of areliability processing method in a MAN providing multi-service. Asillustrated, a VRRP group is established with at least two servicerouters (SRs). Network connections between the UPE and the servicerouters in the VRRP group are established by the Virtual Private LANService (VPLS), respectively.

Two service routers are shown as an example, i.e., the UPE is connectedto two service routers, SR1 and SR2, respectively. The VPLS is runningbetween the service routers and the UPE. The UPE establishes two VPLSPseudo-Wires (PWs) for each accessed service, one to SR1, and the otherto SR2.

One VRRP group is configured between the two SRs. The VRRP grouptransmits the VRRP protocol messages between SR1 and SR2 by the PWs withthe UPE. The BFD for VRRP may be run in order to accelerate thedetection.

According to a VRRP protocol state, the active SR sets its service PWsto an active state, and the standby SR sets its service PWs to a standbystate. The PW in the standby state sends and receives no service messageexcept the VRRP messages.

FIG. 2 is a schematic flowchart of implementing a reliability processingmethod in the Metro Area Network providing multi-service. Asillustrated, the method includes the following steps.

Step 201: A VRRP group is established with at least two service routers,and network connections between a UPE and the service routers in theVRRP group are established by the Virtual Private LAN Service (VPLS),respectively.

Step 202: After the active and standby service routers in the VRRP groupare determined according to a processing result of a VRRP message, Layer2 service and Layer 3 service connections between the service routersand the UPE are established, and the Layer 2 service and Layer 3 serviceprocessing between the active service router and the UPE are performed.

For the Layer 3 service, a service router notifies the UPE, whichestablishes the Layer 3 service connection with the service router. Inthe implementation, for the Layer 3 service, the service router maynotify the UPE of the gateway address via a gratuitous ARP message; forthe Layer 2 service, the UPE broadcasts a message and establishes theLayer 2 service connection with the service router according to aresponse message.

In the implementation, the UPE may be notified that which device is theactive device by a service router. The UPE establishes the Layer 2 andLayer 3 service connections with the active service router according tothe notification, and performs the service processing.

Step 203: When the processing result of the VRRP message varies, theservice router in the VRRP group to establish a service connection withthe UPE is determined according to the message, and the serviceprocessing is commenced.

For the Layer 3 service, the service router notifies the UPE of thegateway address, and the UPE establishes a Layer 3 service connectionwith the service router. In the implementation, for the Layer 3 service,the service router may notify the UPE via the gratuitous ARP message.For the Layer 2 service, after the service router to establish a serviceconnection with the UPE is altered according to the processing result ofthe VRRP message, the altered service router may send a control messageto the UPE by the VPLS control protocol. The UPE relearns the gatewayaddress according to the control message, and commences the Layer 2service processing with the active service router.

In the implementation, after the service router to establish a serviceconnection with the UPE is altered according to the processing result ofthe VRRP message, the altered service router may notify the UPE, whichcommences the Layer 2 and Layer 3 service processing with the servicerouter according to the notification. The altered service router maynotify the UPE via a gratuitous ARP message, and the UPE commences theLayer 2 and Layer 3 service processing with the service router accordingto the gratuitous ARP message.

In the above embodiment, when the network is in a normal operation, theVRRP protocol between the SRs operates normally, and the two SRs are setto the proper active and standby states. For the Layer 3 service, theactive SR sends a gratuitous ARP message to the UPE at the relatedservice PW, so that the service data related to the UPE may betransmitted to the active SR. For the Layer 2 service, the UPE may learnthe MAC address first, and send a broadcast message to SR1 and SR2 viathe two service PWs. The active SR may respond the UPE message, whilethe standby SR performs no processing. As such, after the UPE learns theMAC address from the active SR, the subsequent messages will betransmitted to the active SR device by unicast.

When the active SR is in fault or the network from the UPE to the activeSR is in fault, the standby SR2 is changed to the VRRP active state ifit is unable to receive the VRRP protocol message. Meanwhile, therelated service PW is changed to the active state. After

SR2 is changed to the active state, for the Layer 3 service, agratuitous ARP message is sent to the UPE via the related service PW, sothat the service data related to the UPE may be transmitted to theproper service router. After SR2 is changed to the active state, for theLayer 2 service, a MAC address withdraw message is sent to the UPE bythe VPLS control protocol, so that the UPE may relearn the MAC address,and direct the gateway of the Layer 2 service to SR2.

For the situation where the UPE directs all the egress interfaces forthe Layer 2 and Layer 3 service data to the service PW connected to theactive SR to implement the proper forwarding of data after receiving thegratuitous ARP message issued from the active SR, when the network is innormal operation, the VRRP protocol between the SRs operates normally,and the two SRs are set to the proper active and standby states. Theactive SR issues a gratuitous ARP message, and the UPE directs all theegress interfaces for the Layer 2 and Layer 3 service data to theservice PW connected to the active SR after receiving the message, sothat the subsequent Layer 2 and Layer 3 service data may be forwardedproperly.

When the active SR is in fault or the network from the UPE to the activeSR is in fault, the standby SR2 is changed to the VRRP active state ifit is unable to receive the VRRP protocol message, and sends agratuitous ARP message to the UPE at the same time. The UPE modifies theegress interfaces for all Layer 2 and Layer 3 service data to point tothe service PW connected to SR2 after receiving the gratuitous ARPmessage, so that the subsequent Layer 2 and Layer 3 service data may beforwarded properly.

A reliability processing system in the MAN providing multi-service isalso provided according to an embodiment of the present invention. Theimplementation of the system will be illustrated below in conjunctionwith the drawings.

FIG. 3 is a schematic block diagram of a reliability processing systemin the MAN providing multi-service. As illustrated, the system includesa UPE and at least two service routers, as well as a service switchingmodule.

The at least two service routers form a virtual router Redundancyprotocol (VRRP) group. The UPE establishes network connections with theservice routers in the VRRP group by the Virtual Private LAN Service(VPLS), respectively.

The service switching module determines the active and standby servicerouters in the VRRP group according to a processing result of a VRRPmessage, establishes Layer 2 service and Layer 3 service connectionsbetween the active service router and the UPE, and performs the Layer 2service and Layer 3 service processing.

For the Layer 3 service, the service switching module establishes theLayer 3 service connection between the UPE and a service routeraccording to the notification from the service router, and performsservice processing; for the Layer 2 service, after the UPE broadcasts amessage, the service switching module establishes the Layer 2 serviceconnection between the UPE and the service router according to aresponse message, and performs service processing.

For the Layer 2 service, after the service router to establish a serviceconnection with the UPE is altered according to the processing result ofthe VRRP message, the service switching module switches to the Layer 2service connection between the UPE and the altered service routeraccording to the response message sent by the altered service router bythe VPLS control protocol, and commences the service processing.

The service switching module may also perform the service processing viathe Layer 2 and Layer 3 service connections between the UPE and theservice router according to the notification from the service router.

After the service router to establish a service connection with the UPEis altered according to the processing result of the VRRP message, theservice switching module switches to the Layer 2 and Layer 3 serviceconnections between the UPE and the altered service router according toa notification from the altered service router to perform serviceprocessing.

As apparent from the above embodiments, when the MAN SR is in fault orthe network from the SR to the UPE is in fault, all the Layer 2 andLayer 3 services may be switched to the standby service router quickly,where the switching may be implemented in milliseconds. The servicereliability for the Layer 2 and Layer 3 services of the MAN, includingthe Internet service, VPN service, VOD/VOIP, etc., may be sufficientlyguaranteed. Since the VRRP protocol will not run repeatedly between theservice routers for all the network services for connectivity detection,the overhead of the system may be reduced significantly.

Apparently, various modifications and variations may be made by thoseskilled in the art without departing from the scope of the presentinvention. As such, if these modifications and variations fall withinthe scope of the claims of the present invention and the equivalentsthereof, these modifications and variations are intended to be withinthe present invention.

1. A reliability processing method in networking of a Metro EthernetNetwork providing multi-service, wherein a Virtual Router RedundancyProtocol (VRRP) group is established with at least two service controlgateways, and network connections are established between an accessdevice (UPE) and the service control gateways in the VRRP group by aVirtual Private LAN Service (VPLS), respectively; the method comprising:performing Layer 2 service and Layer 3 service processing after anactive and a standby service control gateway in the VRRP group aredetermined according to a processing result of a VRRP message; wherein,the access device establishes two VPLS Pseudo-Wires (PWs) for eachaccessed service, one is to the active service control gateway, theother to the standby service control gateway; the active service controlgateway sets its service PWs to an active state, and the standby servicecontrol gateway sets its service PWs to a standby state; and the PW inthe standby state sends and receives no service message except the VRRPmessage.
 2. The method of claim 1, further comprising: for the Layer 2service, after the active service control gateway and the standbyservice control gateway are interchanged according to a processingresult of a VRRP message, sending, by the altered active service controlgateway, a media access control (MAC) address withdraw message to theaccess device by a Virtual Private LAN Service control protocol;broadcasting, by the access device, a message to the service controlgateways in the VRRP group by a Virtual Private LAN Servicespseudo-wire; responding, by the new active service control gateway, amessage to the access device; and performing, by the access device,Layer 2 service processing with the new active service control gatewayaccording to the response message.
 3. The method of claim 1, furthercomprising: after the active service control gateway and standby servicecontrol gateway are interchanged according to a processing result of aVRRP message, notifying, by the new active service control gateway, theaccess device of the address of the new active service control gateway;and performing, by the access device, Layer 2 and Layer 3 serviceprocessing with the new active service control gateway according to thenotification.
 4. The method of claim 3, wherein the new service controlgateway notifies the access device by a gratuitous Address ResolutionProtocol message via a service pseudo-wire, and the access deviceperforms Layer 2 and Layer 3 service processing with the new servicecontrol gateway according to the gratuitous Address Resolution Protocolmessage.
 5. The method of claim 1, wherein the VRRP message istransmitted via a pseudo-wire.
 6. A reliability processing system innetworking of a Metro Ethernet Network providing multi-service,comprising an access device (UPE), at least two service controlgateways, and a service switching module, wherein: the at least twoservice control gateways form a Virtual Router Redundancy Protocol(VRRP) group, the access device establishes network connections with theservice control gateways in the VRRP group by a Virtual Private LANService (VPLS), respectively; the service switching module is configuredto perform Layer 2 service and Layer 3 service processing after activeand standby service control gateways in the VRRP group are determinedaccording to a processing result of a VRRP message; wherein, the accessdevice establishes two VPLS Pseudo-Wires (PWs) for each accessedservice, one is to the active service control gateway, the other to thestandby service control gateway; the active service control gateway setsits service PWs to an active state, and the standby service controlgateway sets its service PWs to a standby state; and the PW in thestandby state sends and receives no service message except the VRRPmessage.
 7. The system of claim 6, wherein after the active and standbyservice control gateway are interchanged according to a processingresult of a VRRP message, the service switching module is furtherconfigured to switch to the Layer 2 and Layer 3 service connectionsbetween the access device and the new active service control gateway toperform Layer 2 and Layer 3 service processing according to anotification from the new active service control gateway.
 8. Areliability processing method implemented in a Metro Ethernet Networkproviding for multiple services, the method comprising: establishing aVirtual Router Redundancy Protocol (VRRP) group with at least twoservice control gateways; establishing, by a Virtual Private LAN service(VPLS), network connections between an access device and the servicecontrol gateways; determining an active service control gateway and astandby service control gateway in the VRRP group according to aprocessing result of a VRRP message; performing Layer 2 service andLayer 3 service processing between the active service control gatewayand the access device; establishing, by the access device, a first VPLSPseudo-Wire (PW) and a second VPLS Pseudo-Wire (PW) for each accessedservice, wherein the first VPLS PW is connected to the active servicecontrol gateway and the second VPLS PW is connected to the standbyservice control gateway; setting, by the active service control gateway,the first VPLS PW to an active state; and setting, by the standbyservice control gateway, the second VPLS PW to a standby state, whereinthe second VPLS PW sends and receives the VRRP message; for the Layer 2service, after the active service control gateway and the standbyservice control gateway are interchanged according to a processingresult of a VRRP message, sending, by the altered active service controlgateway, a media access control (MAC) address withdraw message to theaccess device by the second Virtual Private LAN Service controlprotocol; relearning, by the access device, a MAC address; directing, bythe access device, the gateway of the Layer2 service to the alteredactive service control gateway.
 9. The method of claim 8, furthercomprising: after the active service control gateway and standby servicecontrol gateway are interchanged according to a processing result of aVRRP message, notifying, by the new active service control gateway, theaccess device of the address of the new active service control gateway;and performing, by the access device, Layer 2 and Layer 3 serviceprocessing with the new active service control gateway according to thenotification.
 10. The method of claim 9, wherein the new service controlgateway notifies the access device by a gratuitous Address ResolutionProtocol message via a service pseudo-wire, and the access deviceperforms Layer 2 and Layer 3 service processing with the new servicecontrol gateway according to the gratuitous Address Resolution Protocolmessage.
 11. The method of claim 8, wherein the VRRP message istransmitted via a pseudo-wire.
 12. A reliability processing system in aMetro Ethernet Network providing multiple services, comprising: anaccess device; at least two service control gateways; and a serviceswitching module, wherein: the at least two service control gatewaysform a Virtual Router Redundancy Protocol (VRRP) group; the accessdevice establishes network connections with the service control gatewaysin the VRRP group by a Virtual Private LAN Service (VPLS); an activeservice control gateway and a standby service control gateway in theVRRP group are determined according to a processing result of a VRRPmessage; the service switching module is configured to perform Layer 2service and Layer 3 service processing; the access device establishes afirst VPLS Pseudo-Wire (PW) and a second VPLS Pseudo-Wire (PW) for eachaccessed service; the first VPLS PW is connected to the active servicecontrol gateway; the second VPLS PW is connected to the standby servicecontrol gateway; the active service control gateway sets the first VPLSPW to an active state; the standby service control gateway sets thesecond VPLS PW to a standby state; and the second VPLS PW in the standbystate sends and receives the VRRP message; wherein for the Layer 2service, after the active service control gateway and the standbyservice control gateway are interchanged according to a processingresult of a VRRP message: the altered active service control gatewaysends a media access control (MAC) address withdraw message to theaccess device by the second Virtual Private LAN Service controlprotocol; the access device relearns a MAC address and direct thegateway of the Layer2 service to the altered active service controlgateway.
 13. The system of claim 12, wherein the service switchingmodule is configured, for the Layer 3 service, to establish the Layer 3service connection between the access device and the active servicecontrol gateway according to a gateway address notified to the accessdevice by the active service control gateway, and is configured, for theLayer 2 service, to establish the Layer 2 service connection between theaccess device and the active service control gateway according to agateway address obtained from a response message of the active servicecontrol gateway after the access device broadcasts a message; or, theservice switching module is configured to establish the Layer 2 andLayer 3 service connections between the access device and the activeservice control gateway according to a notification of the activeservice control gateway.
 14. The system of claim 12, wherein the serviceswitching module is further configured to establish Layer 2 and Layer 3service connections between the access device and the standby servicecontrol gateway.
 15. The system of claim 14, wherein after the activeand standby service control gateway are interchanged according to aprocessing result of a VRRP message, the service switching module isfurther configured to switch to the Layer 2 and Layer 3 serviceconnections between the access device and the new active service controlgateway to perform Layer 2 and Layer 3 service processing according to anotification from the new active service control gateway.